The increasing rate of obesity has become a major public health concern with national reports indicating 40% of African American adolescents are now overweight or obese. Little is known about effective weight loss interventions in ethnic minority adolescents. In part, this is because research has shown that ethnic minorities attend fewer intervention sessions, have higher attrition rates and lose less weight compared to Caucasians. Two fundamental problems related to this lack of progress are 1) the lack of appropriate content of weight loss interventions for African American adolescents that integrate cultural issues, parenting skills, and motivational strategies for long-term change and, 2) the poor dose of weight loss interventions because of participant fatigue and drop out. Previous weight loss studies among adolescents have been of relatively long duration lasting 12-25 weeks, however, our team has developed a weight loss program that is a relatively brief (8-week brief) face-to-face intervention that integrates motivational (autonomy-support) and positive parenting skills (monitoring, social support, positive communication skills) for reducing z-BMI in overweight African American adolescents. Our team has also recently conducted a pilot study testing the feasibility of an 8-week on-line intervention that is culturally tailored fr African American families. Thus, the goal of this project is to conduct a randomized controlled efficacy trial to address the problems with past studies by 1) making the face-to-face group intervention shorter, 2) using an on-line component to compliment the group- based intervention for increasing dose, and by 3) tailoring a motivational and parenting skills program directly to parents and adolescents skill levels and cultural background. 520 overweight African American adolescents and their parents will be recruited to participate. Phase I of the trial will test the efficacy of an 8-week face-to-face group randomized trial comparing motivational plus family-based weight loss (M+FWL) to a basic health (BH) education program on reducing z-BMI and improving diet and physical activity (PA) in overweight African American adolescents. In phase II of the trial participants will be re-randomized to either an 8-week on-line intervention or a control on-line program resulting in a 2 (M+FWL vs. BH group) x 2 (intervention vs. control on-line program) factorial design. This design will allow us to test the effects of the M+FWL curriculum and the added effects of the on-line intervention component on reducing z-BMI in African American adolescents and their parents. A 6-month follow-up will examine whether adolescents in the 8-week M+FWL group plus 8-week on-line intervention program will show the greatest maintenance in reducing z- BMI. Psychosocial mediators of treatment effects will be examined as well as treatment effects related to parent changes in z-BMI and health behaviors (diet and PA). PUBLIC HEALTH RELEVANCE: The proposed efficacy trial will address an important public health problem for developing cost-effective interventions to decrease obesity in underserved adolescents (low income, minorities).